The planning and management of data centers is a complex task which involves various aspects that have to be considered. Primarily, the storage capacity and the computing power of a data center has to be planned in such a way that the data center is capable of fulfilling its requirements. Therefore, appropriate network devices such as servers, specially designed storage devices and interconnect devices (routers, switches, hubs, etc.) which constitute the data center should be selected prudently. After the data center has been put into operation, the data center may be managed by administrators supported by network management platforms such as Hewlett Packard's OpenView. A network management platform is typically capable of querying management information (type of device, manufacturer, status: up or down) of the individual network devices, analyzing the queried data and providing a real-time monitoring of the functioning of the network devices based on the analysis of the queried management information.
The planning and management of data centers are interrelated in that a well conceived data center is less error-prone and needs less supervision by human data center administrators. Moreover, the costs of the data center personnel, lease rental charges of the floor space occupied by the network devices, electric power consumption of the network devices and some other sizes—commonly subsumed under the term “maintenance costs”—may be cut.
In this context, curbing the electric power consumption of a data center is important, for example, since it correlates with the heat radiated by the network devices. Therefore, if the electric power consumption is high, the air conditioning system of the data center also needs more electric power to cool the ambient temperature down and keep it below a threshold in order to prevent the network devices from breaking down as a result of overheating.
At present, the electric power consumption of the network devices of a data center is normally not a constant value and in the future, the electric power consumption of a data center will be subject to even more variations since next-generation network devices will increasingly make use of on-demand computing features or will dynamically power down non-utilized devices such as CPU's and hard disks.
In one approach to determining the electric power consumption of a data center (i.e. the total electric power consumption of all network devices), the data center personnel manually creates an inventory of all data center equipment and calculates the total amount of power consumption of all devices. This approach is both labor intensive and error-prone. Furthermore, since network devices may be added to or removed from the data center, the electric power consumption of the data center thus determined may only be valid for a short period of time.
In U.S. Pat. No. 6,836,737, a plurality of power meters may be monitored remotely by a host computer. The electric power meters are configured to measure the electric power consumption of loads attached to them. In this context, a load is typically one or several electricity-consuming devices belonging to a household. The electric power meters send their measured data via transceivers connected to a WAN (wide area network) to the host device which evaluates the data. Each power meter needs its own address in order to be queryable via a network communication protocol.
Another system which enables polling of electric power consumption of network devices is “Power over Ethernet”. This technology pertains to a system that transmits electrical power, in addition to data, to remote devices over standard twisted-pair wire in an Ethernet network. This technology is useful for powering IP telephones, wireless LAN access points, webcams, hubs, and other appliances where it would be inconvenient or infeasible to supply power separately. The Power over Ethernet technology was originally developed and first delivered by Cisco to support IP telephony. Telephones are connected to Cisco switches and the Cisco Discovery Protocol (CDP), a network protocol acting on OSI Layer 2, is provided which is used by Cisco routers to obtain protocol addresses of nearby devices. The electric power consumption of the telephones connected to a switch may be queried by a network management application.